# Frame time

## Definition

FLOAT frame_time

Frame_time is a global variable, holding the time passed the last frame. In other words: the difference in time between the start of the last frame and the current frame.

Doing a bit of physics, we see that:

FPS = 1 / frame_time

Be advised that frame_time is in milliseconds accurate, so it can be 0 at times, so one might prevent such a case from happening:

FPS = 1 / ( frame_time + (frame_time==0)*0.0001 );

This gives a sort of FPS which is accurate every frame.

## Example

Display how long the program has been running, by use of frame_time:

```Program timers;
Private
int ft; // Help variable
int i;  // how long the program has been running in 1/100s
float f; // how long the program has been running in 1/100s
Begin

set_mode(320,400,8);
write_int   (0,0,300,0,&timer);
write_int   (0,0,310,0,&i);
write_float (0,0,320,0,&f);

Repeat

// Calculate how long the program has been running in 1/100s without a float
ft %= 10; // keep the milliseconds from last time
ft += frame_time*1000; // add the last passed time to it in milliseconds
i += ft/10; // add it to the integer without the milliseconds

// Calculate how long the program has been running in 1/100s with a float
f+=frame_time*100;

frame;
Until(key(_ESC))

End
```

Used in example: set_mode(), write_int(), write_float(), key(), timer

Let a process wait for a certain time by calling this function:

```Function int wait(float seconds)
Begin
While( (seconds-=frame_time) > 0 ) frame; End
return -seconds;
End
```

This can be done with a timer too, as is displayed here.